Tillage intensity reductions when combined with yield increases may slow soil carbon saturation in the central United States

Authors: JOSHI, DEEPAK - South Dakota State University; CLAY, DAVID - South Dakota State University; ALVERSON, RON - Farmer; CLAY, SHARON - South Dakota State University; WESTHOLF, SHAINA - South Dakota State University; Johnson, Jane; WANG, TONG - South Dakota State University; SIEVERDING, HEIDI - South Dakota School Of Mines And Technology

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2025
Publication Date: 3/28/2025
Citation: Joshi, D.R., Clay, D.E., Alverson, R., Clay, S.A., Westholf, S., Johnson, J.M., Wang, T., Sieverding, H. 2025. Tillage intensity reductions when combined with yield increases may slow soil carbon saturation in the central United States. Scientific Reports. https://doi.org/10.1038/s41598-025-95388-x.
DOI: https://doi.org/10.1038/s41598-025-95388-x

Interpretive Summary: Since the 1970’s, increasing number of farmers have been planting seeds with high yield potential, using cover crops to provide soil cover, and reducing their reliance of tillage to prepare a seedbed. In many fields, these practices have increased yields and decreased the impact of agriculture on the environment. This study investigated if these practices also help mitigate global warming while increasing food production. This study showed that in Nebraska, Iowa, Minnesota, and South Dakota, increasing corn and soybean yields when combined with reduced tillage intensity, resulted in soil organic carbon (SOC) levels that increased at a rate of 267 pounds per acre a year between 1999 and 2020. This translates into millions of tons of carbon moved into the soil as organic matter. These results were attributed to a feedback loop between higher corn and soybean yields and reduced tillage intensity, leading to increased SOC amounts and permanence, higher yield potentials, and reduced erosion. However, because soil samples were only collected from the surface 15 cm, additional research that samples the entire soil profile is needed to confirm the findings. These finding are of interest to producers, scientists and policy makers.

Technical Abstract: Efforts to increase food production has often resulted in short-term food production increases followed by gradual declines. This is not a viable option when addressing the combined problems of global warming and producing food for a growing population. A potential solution for both issues is to increase the soils organic carbon content. There are several questions associated with increasing soil organic carbon including how much and how long carbon can be stored in soil. Therefore, the purpose of this paper is to review soil organic C storage and assess the feasibility of long-term carbon storage or permanence over a large geographic area. Published papers have shown that soil organic carbon can exist in soil for hundreds or even thousands of years, that long-term storage or effective permanence can be achieved by replacing oxidized organic carbon with non-harvested plant residues, and that soil organic carbon storage decreases with increasing tillage intensity. Carbon effective permanence was evaluated by comparing over 12 million surface (0- to 15- cm) soil samples collected for fertilizer recommendations between 1999 and 2020 in Nebraska, Iowa, Minnesota, and South Dakota. This analysis showed that from 1999 to 2020, surface soil organic carbon (SOC) increased at rates of 311 ±107, 465 ±75; 467 ±101, and 447 ±105 kg/(ha×year) in Nebraska, Iowa, Minnesota, and South Dakota, respectively. Associated with increasing soil organic carbon were corn (Zea mays) yields that increased at rates of 156±49, 127 ±65, 135 ± 56, and 173±65 kg grain/(ha×year), and soybeans (Glycine max) yields increased at rates of 56.5±20, 39.6 ±22, 34.5 ± 18.2, and 43.9±19.4 kg grain/(ha×year), in Nebraska, Iowa, Minnesota, and South Dakota, respectively. These findings suggest that from 1999 to 2020 effective permanence was achieved by a feedback loop between genetic improvements that increased non-harvested organic C left in the field and reduced tillage intensity that reduced the mineralization of soil organic carbon. Over the 4 states and 20 years, over 1.12 billion metric tons of CO2 were stored in the surface 15 cm. However, because only the surface 15 cm were sampled, these findings need to be confirmed by additional studies that assess the entire soil profile.